Roots vs Leaves

There's a common belief among local cassava growers that healthly leaves and long branches are bad to have because growth energy is being expended above ground instead of into the roots which are dug up and sold by the weight.
I think the truth is more complicated. The chemistry of what makes roots grow large and the dynamics of above-the-ground development are not the same. Soil condition (texture, composition, organic content) and correct fertilizer application are the most important factors for root growth.

There is also the matter of moisture content. When roots are transported to the factory, they are sampled and tested; the higher the moisture, the lower the price. This is why farmers usually wait for several hot and dry days before harvesting. Sun dried cassava chips sell for 4 to 5 times per kilo more than raw roots.

Among the crops, cassava is considered safe and easy to grow, and it requires a relatively small investment. Cut the stems into 15 centimeter sections, poke them into the soil in neat rows, and voila! you're a cassava farmer. But because risks and investment cost are low, so is the profit margin, though it is generally high enough to make growing cassava a viable business venture.

Market mechanisms in Thailand's agricultural sector are reasonably efficient and risk and reward ratios of various plants are well correlated with expected returns on investment.

Photo location: Baan Hintoom, Uthaitani province (If you click on the picture, you'll see a cute little bug on a leaf. The bug, not the leaves, is the reason why I took this picture.)